Ah. It's been a while since I played with Hummingbird, but I seem to recall that it has both VT100 and TN3270 APIs available. Depending on which kind of terminal the mainframe expects to be talking to, you will be able to use the 'native' API-calls to scrape the data into a character string that you can manipulate with Perl.
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I Go Back to Sleep, Now.
OGB